Question

I have scheduled a timer using [NSTimer scheduledTimerWithTimeInterval:target:selector:userInfo:] and want to invalidate it at some point when it fires.

- (id)init
{
    [NSTimer scheduledTimerWithInterval:1 target:self selector:@selector(fired:) userInfo:nil repeats:YES];
}

- (void)fired:(NSTimer *)timer
{
    if (someCondition) {
        [timer invalidate];
    }
}

Is this allowed? The documentation states

You must send this message from the thread on which the timer was installed. If you send this message from another thread, the input source associated with the timer may not be removed from its run loop, which could prevent the thread from exiting properly.

If this is not a proper way to accomplish this task: What is the proper way?

Answer 1

It is fine to invalidate it from the fired method, as the fired method is on the same thread the timer was scheduled on:

scheduledTimerWithTimeInterval:target:selector:userInfo:repeats:

Creates and returns a new NSTimer object and schedules it on the current run loop in the default mode.